Yellowstone National Park is at high altitude. Most of the park is above
7,500 feet / 2,275 meters. High altitude means cooler temperatures. Yellowstone's
weather is unpredictable. In summer, it may be warm and sunny with temperatures
in the high 70s / 25° C. At night in any given month, the temperature
may drop close to freezing (32° F / 0° C). So it is best to come
prepared for cold evenings and mornings, especially if you are camping
or hiking. When you leave your campsite, please leave it prepared for
possible thundershowers and wind.

Spring Weather

Cold and snow linger into April and May, although temperatures gradually
climb. Average daytime readings fall in the 40s to 50s / 5 - 15° C,
reaching the 60s and 70s / 15 - 25° C by late May and June. Overnight
temperatures fall below freezing and may plunge near 0° F / -20°
C. These are statistical averages; actual conditions can be vastly different
from long term "norms." At any time of year, be prepared for
sudden changes; unpredictability, more than anything else, characterizes
Yellowstone's weather. Storms in late May and early June may result in
significant accumulations of snow--up to a foot of snow in 24 hours is
not uncommon.

Summer Weather

Average maximum summer temperatures are usually in the 70s / 25°
C and occasionally in the 80s / 30° C in the lower elevations. Nights
are cool and temperatures may drop into the 30s and 40s / 0 - 10°
C. Depending on the elevation, temperatures may even fall into the 20s
/ -5° C with a light freeze. June can be cool and rainy; July and
August tend to be somewhat drier, although afternoon thundershowers and
lightning storms are common. During lightning storms get off water or
beaches and stay away from ridges, exposed places, and isolated trees.
At any time of year, be prepared for sudden changes; unpredictability,
more than anything else, characterizes Yellowstone's weather.

Fall Weather

Fall weather can be pleasant, although temperatures average 10 to 20
degrees lower than summer readings--highs in the 40s to 60s / 5 - 20°
C. Over night temperatures can fall into the teens and single digits /
-10° to -20° C. Snowstorms increase in frequency and intensity
as the weeks go by. At any time of year be prepared for sudden changes;
unpredictability, more than anything else, characterizes Yellowstone's
weather.

Winter Weather

Winter temperatures often hover near 0° F / -20° C throughout
the day but may reach highs in the 20s / -5° C. Subzero over night
temperatures are common. Occasionally, warm "chinook" winds
will push daytime temperatures into the 40s / 5 - 10° C, causing significant
melting of snowpack--especially at lower elevations. Yellowstone also
typically experiences periods of bitterly cold weather. The lowest temperature
recorded in Yellowstone was -66° F / -54° C near West Yellowstone
on 09 Feb 1933. Annual snowfall averages near 150 inches / 380 cm in most
of the park. At higher elevations, 200-400 inches / 5 - 10 meters of snowfall
have been recorded. At any time of year, be prepared for sudden changes;
unpredictability, more than anything else, characterizes Yellowstone's
weather.